1. Field of the Invention
The present invention relates to an inkjet head cleaning device and cleaning method, and an inkjet printing device, and particularly relates to head cleaning technology for wiping a nozzle surface of an inkjet head using a wiping member supplied with cleaning liquid.
2. Description of the Related Art
A dirty nozzle surface (surface where a nozzle is formed) of a head in an inkjet printing device causes ejection failure. For this reason, the nozzle surface is periodically cleaned.
As a method for cleaning the nozzle surface, there have been known in the past a cleaning method of wiping the nozzle surface by a blade, a cleaning method of wiping the nozzle surface by a web, and the like.
Japanese Patent Application Laid-Open No. 2010-274533 (PTL 1) discloses a head maintenance device including a drop nozzle dropping cleaning liquid that is an ink solvent onto a cleaning cloth, in which the cleaning cloth in a state of being wetted with the ink solvent is conveyed to a cleaning position to absorb and remove the ink droplet on the nozzle surface.
According to the technology in PTL 1, even if the ink droplet deposited on the nozzle surface becomes thickened due to a dry atmosphere or the like, a concentration difference between the cleaning liquid seeping into the cleaning cloth and the thickened ink droplet generates an osmotic pressure action such that the ink droplet deposited on the nozzle surface is effectively absorbed and removed.
However, in the technology in PTL 1, a mixed liquid of the ink and the cleaning liquid remains on the head nozzle surface after cleaning in some cases. If the mixed liquid remains on the head nozzle surface, problems may occur, for example, the mixed liquid is connected with meniscus of the nozzle, the mixed liquid remaining on the nozzle surface is dried and gets into the nozzle in wiping next time, a long time contact between the nozzle surface and the mixed liquid causes a liquid repellent film of the nozzle surface to deteriorate, and the like.
Therefore, in order to prevent the mixed liquid from remaining on the nozzle surface, physical properties of the mixed liquid need to be considered.
On the other hand, Japanese Patent Application Laid-Open No. 2006-205714 (PTL 2) discloses a technology in which a surface is cleaned by supplying head liquid to a surface of an inkjet head and performing wiping operation such that relationship among surface tension of the surface of the inkjet head, surface tension of an ink, and surface tension of the head liquid satisfies a predetermined condition, and thereby, surface tension of an ink residue mixed liquid with respect to a deposited surface is made higher than that of the ink residue only, and materials of a wiper blade are selected in terms of the ink residue mixed liquid.
According to the technology in PTL 2, the mixed liquid can be easily removed from the nozzle surface.